Large size full color projections of information data find important application to the fields of air traffic control for both commercial and military purposes. Information provided at the output of a cathode ray tube, which is used to radar scan a large information field, for example, can in turn be projected upon a large wall-sized screen for observation and surveillance by a group of controllers. When the cathode ray tube output data is color augmented and interfaced with a computer traffic control pattern it can be instantly analyzed for conformance to pre-arranged control patterns. If an unscheduled or otherwise unidentified aircraft should stray into the information pattern being displayed then the "unidentified" aircraft could be represented in a contrasting color (usually red) to other aircraft in the viewing field.
The use of group display generators for military purposes is particularly important in view of early warning and countermeasure applications. In miliary applications, for example, mobile ships and planes could constantly scan preassigned locations and project the information concerning flight activity within these locations to a selected group of personnel. Here unidentified aircraft portrayal in contrasting colors would alert military personnel as to effective countermeasures if any should become necessary.
Current methods for projecting full color displays from the output of cathode ray tube faceplates use wet chemistry film developing techniques in order to provide a permanent film record of the information received from the cathode ray tube faceplate. The data present on the cathode ray screen is projected simultaneously through three separate monochromatic lenses to three different color assignment areas onto a light sensitive black and white film. The film is usually transferred to a wet chemical solution for developing and printing and from there to an optical projection system consisting of projection lamps and colored filters for converting the monochromatic color assigned areas on the film to color and transmitting the film image in color upon a wall-sized viewing screen.
This method is very efficient for producing large size reproductions of the details appearing upon the face of the cathode ray tube and provides useful information in view of the good definition and contrast occurring in the projected image. However, in certain applications, a dry film process is necessitated since space requirements do not permit the facilities that are required by the large amount of apparatus and materials necessary for the wet chemical film developing process. In mobile applications upon ships, submarines and aircraft, where group display generators find particular application, dry film processes must be employed because of the serious space storage limitations involved.
The present state-of-the-art of dry film processes for the development of silver halide films are not very efficient in view of the limited image amplification by the dry film technique. Whereas wet chemical processes are capable of image amplification in the order of 1,000,000, the dry film development process is limited to the order of 1,000. It quite often occurs that the dry film limited sensitivity renders group display generator applications ineffective since the low level brightness available on the face of the cathode ray tube faceplate is incapable of transferring sufficient illumination to the surface of the film during exposure to provide meaningful data when the exposed film is later developed by the dry process at the inherently low image amplification available. The developed and printed film in most group display generator systems is placed between an array of projection lenses and a strong source of projected light. The energy supply for projected viewing therefor is independent of the film developing process and finds more than sufficient intensity in view of the high intensity projection lamps available. The ineffectiveness of dry film development applications therefore is due to both the inherently low level illumination provided upon the face of the cathode ray tube display screen and the low image amplification factor inherent in current dry film and dry film processing techniques.
The purpose of this invention, therefore, is to provide a novel arrangement for additive color projection by means of an image intensifier augmented cathode ray tube and dry film recording process, whereby adequate film surface illumination is provided by an image intensifier to overcome the inherent low image amplification factor of the dry silver halide film process.